Tommy Smothers, along with his brother Dick, make up the comedy act, The Smothers Brothers, which had a show on CBS in the 1960s. Both are outspoken liberals who generated a lot of controversy on their show with anti-Vietnam War, anti-Nixon, anti-anyone to the right of George McGovern rhetoric.
For Jillette, Tommy Smothers, the comedian, is someone he grew up idolizing. Recently, they were on some sort of talk show together and the subject of Penn's appearance on the Glenn Beck show came up. In the video, Jillette explains how it went to hell (WARNING: Strong language):